In conventionally proposed games, items are awarded when various types of events, such as searching and battling, are achieved. For example, Non-Patent Document 1 proposes a game in which various types of privileges are granted to a player when he or she collects (that is, completes) all types of items in one group (hereafter called an item group). In the game disclosed in Non-Patent Document 1, a player who wins in a battle event in which a plurality of players participate acquires an item owned by a defeated player.